For +11, your meister needs to be +10 and the fodder also needs to be +10. The fodder can be any item as long as it is the same level and grade as the meister. Legend 130 meister with legend 130 fodder equipment, etc. Contrary to rumours, the fodder does not to be meister.

For +12, your meister needs to be +11 and the fodder just +10. Same requirements for grade and level.